Apparatus for forming thin plastic packaging trays

ABSTRACT

A machine for forming thin plastic packaging trays of dished configuration with an upper peripheral edge which lies within a single plane The machine includes a plurality of flat faced vacuum form molds carried on the periphery of a rotating drum. A ribbon of plastic material is continuously delivered to the drum and mechanically clamped to the surface of each mold in consecutive order as the drum rotates. Each section of clamped ribbon is carried past a radiant heater and a vacuum is then applied to draw the softened plastic into the mold. The clamps are disengaged and the trays are held in the molds by a continued application of vacuum while a heated blade moving in a repetitive closed curvilinear path severs the ribbon between adjacent trays and while a pair of rotating knives trim the edges of the trays. A vacuum operated picker removes the trays from the drum and deposits them on a conveyor.

United States Patent [1 1 Pinto et al.

[ Nov. 1-3, 1973 APPARATUS FOR FORMING THIN PLASTIC PACKAGING TRAYS I[76] Inventors: Albert Pinto, White Plains, N.Y.;

Related [1.8. Application Data [63] Continuation of Ser. No. 96,568,Dec. 9, 1970,

abandoned.

[52] US. Cl. 425/174 HR, 425/292, 425/294, 425/302, 425/388, 425/397,264/92 [51] Int. Cl. B29c 17/04 [58] Field of Search 425/174, 195, 292,425/264, 388, 397, 302; 83/171; 264/163, 90, 92

[56] References Cited UNITED STATES PATENTS 3,026,566 3/l962 Martelli eta1. 425/388 X 3,054,441 9/1962 Gex et al. 83/17I X 3,218,776 ll/l965Cloud 53/30 3,369,274 2/1968 Dicks et a1 425/174 3,479,694 11/1969Winstead 425/388 X 3,518,334 6/1970 Carrigan et al. 425/195 XDonafrio...... 425/195 X Olson et al 83/171 Primary Examiner-RobertSpicer, Jr. AttorneyGerald Durstewitz et al.

[57] ABSTRACT A machine for forming thin plastic packaging trays ofdished configuration with an upper peripheral edge which lies within asingle plane The machine includes a plurality of flat faced vacuum formmolds carried on the periphery of a rotating drum. A ribbon of plasticmaterial is continuously delivered to the-drum and mechanically clampedto the surface of each mold in consecutive order as the drum rotates.Each section of clamped ribbon is carried past a radiant heater and a 10Claims, 23 Drawing Figures United States Patent 1 [111 3,771,938 Pintoet a]. Nov. 13, 1973 PATENTED "UV 1 3 I973 SHEET 2 BF 9 PATENTEI] NOV 13 I975 3.771.938 SHEET 90F 9 INVENTORS 415677- A Paw- 14 APPARATUS FORFORMING THIN PLASTIC PACKAGING TRAYS RELATED U.S. APPLICATION This is acontinuation, of application Ser. No. 96,568, filed Dec. 9, 1970 nowabandoned.

BACKGROUND OF THE INVENTION The present invention relates to vacuumforming of articles from thin plastic material, and, more particularly,to machinery for forming articles having a shape which requires the useof flat faced molds.

The type of article which the present invention is principally concernedwith is a generally pan shaped packaging tray having an upper peripheraledge which lies substantially within a single plane. These trays arecommonly used in the packaging of articles such as cookies or crackers.The vacuum forming of such trays requires the use of a mold having aflat face upon which the upper peripheral edge of the tray is formed.

In the past, trays of this type have been formed from rectangular sheetsof plastic by machines which operate in a reciprocating manner. In theprior art machines a reciprocating mechanism removes a single plasticsheet from a stack and places it on a mold where it is heated andsubjected to vacuum to draw the softened plastic into the mold cavity. Areciprocatingtrimming die then descends upon the mold to remove thesurplus plastic at the edges and produce rounded corners on theperipheral edge of the tray. The finished tray is lifted from the moldand transported by another reciprocating mechanism to a conveyor. Thetray is subsequently filled with articles and slipped into a tubularenvelope which is then sealed to complete the packaging.

The tubular envelope is sized to closely fit the filled tray and isnormally made of a thin transparent material such as cellophane. It isextremely important therefore that the corners of the trays be roundedto guide the tray into the envelope and to remove any danger of the.

envelope being torn by a sharp-corner during this operation. Y

T hecost of any product is a function of (among other factors) the costof the raw materialsand theitirnerequired to convert thev raw materialsinto the finished product.

The plastic used in the prior art machines is manufactured in longribbons which must be sliced and stacked for use by a reciprocatingmachine. The cost of the plastic sheets is therefore significantlyhigher than a comparable quantity of the ribbon which is merely woundonto a roll.

It is well known that a continuously operating rotary machine isgenerally capable of faster operation than a reciprocating machineperforming'the same function. Rotary machines are therefore'preferredwherever the function of a machine lends itself to rotary operationbecause of the decrease in unit cost of the articles manufactured.

It has long been evident that plasticpacking trays of the type underdiscussion would be significantly less expensive if they could beproduced by a rotary machine which accepts the raw material plastic inribbon form. However, there are a number of factors and requirementsinvolved in the production of these trays which mitigate against the useof high speed rotary machinery employing the modes of operationdisclosed in the prior art.

United States Pat. No. 3,218,776 issued on Nov. 23, 1965 to C. E. Clouddiscloses a rotary machine which represent the state of the art in thisgeneral field. The machine utilizes a rotary drum having a cylindricalouter surface in which mold cavities are formed. A ribbon of plastic isfed between a heated roller and the drum and a vacuum draws the softenedplastic into the mold cavities. The trays thus formed are filled andwiper blades (mounted in contact with the drum) spread the fillingmaterial into the corners of the tray. A second ribbon of plastic is fedbetween a roller and the drum to seal the packet and a third rolleroperates to loosen the packet from the mold. A set of stationary knifeblades and a set of rotary knives separate adjacent packets andcompressed air is employed to drive the packets out of themolds onto aconveyor.

The machine of the type shown in the Cloud patent could not be used toproduce the type of packaging tray with which the present invention isconcerned for a number of reasons. I

The requirement that flat faced molds be used in forming the trayseliminates the possibility of employing a drum with a cylindricalsurface against which rollers can operate to handle or work the plasticraw material or the formed trays. The placement of flat faced molds onthe outer periphery of a drum produces a surface composed of a series offlat sections which rollers could not follow during high speedoperation. Thus, the means shown in the prior art. patent for applyingthe plastic ribbon to the drum, for heating the ribbon, and

'for securing th plastic during the forming operation could not be usedwith a machine employing flat face molds.

Some of theother reasons which prevent the Cloud machine from being usedfor the purposes of this invention are the requirements that the traysbe trimmed to provide round corners, that the trays leave the machineempty and are placed on a conveyor in an upright position, and thatduring the transfer to the conveyor the extremely light weight trays maynot be affected by the air currents generated during high speedoperation of the machine. I I

SUMMARY In view of the foregoing, an object of the present invention isto provide a continuously operating rotary machine for producing thinplastic articles having a shape requiring molding on a flat faced mold.

Another object is to provide such a machine in which a series of flatface molds are mounted on a rotary drum and novel mechanisms areprovided for cooperating with said molds to form individual trays from aribbon of plastic material.

Another object is to provide such a machine including means fordepositing the formed trays on a conveyor in position for filling.

. Another object is to provide novel apparatus for clamping a sheet ofmaterial to the peripheral surface of a rotary-drum.

Other and further objectsof the-invention will be obvious upon anunderstanding of the illustrative embodiment about to be described, orwill be indicated in the appended claims, and various advantages notreferred to herein will occur to one skilled in the art upon employmentof the invention in practice.

The foregoing objects are generally accomplished by providing a machinecomprising a rotary drum carrying a plurality of outwardly facing flatfaced vacuum form molds spaced about the periphery of said drum, meansfor continuously rotating the drum at a uniform speed, means forcontinuously applying a ribbon of thin plastic material to the drum tocover'the molds, means for mechanically clamping the ribbon to the drum,means for heating the ribbon after clamping, means for applying a vacuumto the molds to draw the heated film into the mold, means for trimmingand separating the formed trays, and means for removing the individualfinished trays.

BRIEF DESCRIPTION OF THE DRAWING A preferred embodiment of the inventionhas been chosen for purposes of illustration and description, and isshown in the accompanying drawing, forming a part of the specification,wherein:

FIG. 1 is a front elevational view, partly in section, of a machineaccording to the present invention showing the position of the majorcomponents thereof and illustrating the sequence of operation;

FIG. 2 is a rear elevational view of the machine, also partly insection, further illustrating the construction of the mechanism foroperating the jaws which clamp the plastic ribbon during the heating andvacuum forming operations;

FIG. 3 is a view taken along line 33 on FIG. 7 showing details of thejaw operating mechanism;

FIG. 4 is a plan view of one of the jaws shown in FIG.

FIG. 5 is a sectional view taken along the line 55 on FIG. 4 showing apair of jaws clamping the plastic ribbon onto a mold block during theheating operation;

FIG. 6 is an enlargement of a portion of FIG. 5;

FIG. 7 is a sectional view taken along line 77 of FIG. 1 showing theconstruction of several mechanisms of the machine and the condition ofthese mechanisms during the heating operation;

FIG. 8 is a plan view of a mold block employed on the machine; l

FIG. 9 is a sectional view taken along line 9--9 on FIG. 8;

FIG. 10 is a sectional view taken'along line 10-10 on FIG. 9;

FIG. 11 is a perspective sectional view of a finished packaging traywith the removed portion of the tray shown in phantom;

FIG. 12 is a view taken along line l212 on FIG. 1 showing the conditionof the clamping jaws just prior to trimming the formed tray, and alsoshowing the cam arrangements controlling the movement of the trimmingblades;

FIG. 13 is a view taken along line l3-13 on FIG. 12 showing the camcontrolled mechanism which carries and positions the lateral trimmingblade;

FIG. 14 is a view taken along line 14 14 on FIG. 13 providing a planview of the blade positioning mechanism;

FIG. 15 is a view taken along line 1515 on FIG. 14 illustrating theposition of the-transverse blade relative to a mold block during thetrimming operation, the formed tray being deleted from this view for thesake of clarity;

FIG. 16 is a view taken along line l6-16 on FIG. 15 further showing theposition of the blade edge with respect to the mold blocks, the formedtray also being deleted from this view;

FIG. 17 is a sectional view taken along line 17-17 on FIG. 16illustrating the central portion of the transverse blade cutting thesheet material between adjacent mold blocks to separate adjacentlyformed trays;

FIG. 18 is a view taken along the line l818 on FIG. 16 illustrating theend portions of the transverse blade cutting a rounded corner at theedge of a formed tray;

FIG. 19 is a view taken along the line 1919 on FIG. 1 showing themechanism controlling the edge trimming knives;

FIG. 20 is an enlarged front view partly in section, taken along theline 20--20 0n FIG. 19;

FIG. 21 is a plan view taken along line 21-21 on FIG. 20 illustratingthe relationship of the cuts made by the edge trimming knives to thosemade by the transverse blade;

FIG. 22 is a front elevational view of the mechanism for removing theformed trays from the mold blocks;

FIG. 23 is a sectional view taken along line 2323 on FIG. 22.

Referring now to the drawings, there is shown a machine in accordancewith the present invention for producing the thin plastic packagingtrays depicted in FIG. 11. With reference to FIG. 1, a brief descriptionof the machine will now be provided to give a general understanding ofits construction and operation to be followed by a detailed descriptionof each mechanism. The machine is assembled on a pair of frame endplates 10 and 11. A rotating drum 12 is mounted between the end platesand carries twenty flat faced vacuum form molds 13 which are mountedabout the periphery of the drum to form the outer surface thereof. Themolds are spaced apart to provide slots 14 therebetween for reasonsdescribed hereinafter. A rotating roller 15 is mounted between the endplates 10 and 11 to guide a ribbon 16 of thin plastic material from aroll (not shown) onto the peripheral surface of the drum to cover themolds 13. On opposite sides of each mold, a clamping assembly 17 ismounted to the drum to clamp the edges of the ribbon 16 to the mold 13.A heating assembly 19 is mounted on the frame member 11 to heat andsoften the ribbon as it is rotated past the assembly, and a vacuum isthen applied to each mold in turn, as described hereinafter in detail,to draw the softened plastic into the mold cavity. The vacuum formingprocess converts the ribbon into a series of connected trays havingsurplus plastic along the edges thereof where the ribbon is clamped.After the trays are vacuum formed, the clamping assembly is released andthe vacuum is continuously applied to the molds to hold the traysthroughout severing and traimming operations which follow. A transversesevering mechanism 20 is positioned adjacent to the top of the drum andrepetitively moves a heated blade 21 through a closed curvilinear pathto sequentially mesh with each of the slots 14 as they pass and thussever the plastic strip connecting adjacent trays. The surplus plasticat the edges of the trays is next removed by the operation of an edgetrimming mechanism 22 which includes a pair of rotating knives 24. Thefinished trays are removed from the drum by a rotating picking wheel 25having a plurality of vacuum picking arms 26 which engage the trays andtransfer them to a conveyor belt 27.

The drum 12, the feeding roll 15, and the picking wheel 25 are driven byan electrical motor 29 through a speed reducing gear The 30. the inputshaft 31 of the gear train is driven by the motor through a belt 32. Agear 34 mounted on the output shaft of the gear train drives a train ofthree gears 35, 36 and 37 of equal diameter. The gear engages and drivesa gear 38 mounted on the shaft of the roller 15. The gear 36 engages anddrives a gear 39 connected to the drum 12. The gear 37 engages anddrives a gear 40 connected to the picking wheel 25. The motor 29 and thegear train 30 are mounted between the end plates 10 and 1 1 while thegears 34 through 40 are positioned-adjacent the outside surface of theend plate 10.

THE DRUM 12 Referring now to FIG. 7, the drum 12 is mounted on a shaft42 extending betweenv the frame plates 10 and 11 and comprises a sleeve43 and a pair of end walls 44 and 45 which are welded to opposite endsof the sleeve. The sleeve 43 is locked to the shaft 42 by a key '46 andthe shaft is journalled in bearings-48 and 49 carried by the end plates10 and 11. The gear 39 is secured to the left end of the shaft as viewedin FIG.'7. The outer periphery of each of the end walls 44 and 45consists of twenty flat surfaces 50 of equal length (see FIG. 3) uponwhich the molds 13 are mounted.

THE MOLDS 13 As shown in FIGS. 8 through 10, each of the molds 13 are offlat rectangular construction having end flanges 51 and 52 provided withbolt holds 53 (by means of which the molds are mounted to the drum) andhaving a center cavity section 54. Three elongated cavities 55, 56 and57 formed in the cavity section 54 extend across the mold between theflanges. A pair of grooves 59 and 60 formed in the top surface of themold define the edges of the cavity section 54. The ends of the groovesflare inwardly to produce beveled corners 61 on the cavity section toallow the transverse severing mechanism 20 to produce rounded corners onthe trays as described hereinafter.

The cavity section 54 is provided with an upper flat surface 63 whichextends completely around the periphery of the cavity section and aroundeach of the cavities 55, 56 and 57. The cavities 55, 56 and 57 aresemi-circular in cross section and are formed with a series of grooves64 spaced along the length the'reof The cavity 56 is formed with alongitudinal groove 65 extending along the bottom thereof to addstiffness to the finished tray. A large rectangular cavity 66 isprovided in the bottom of the mold and is connected to each of thecavities 55-57 by a series of passageways 67. Rectangular formations 69and 70 are provided on the lower surface of the flanges 51 and 52 alongthe edges of the cavity 64 to engage the inner surfaces of the drum endwalls 44 and 45. As shown in FIGS. 5, 7, l2

and 15, the flanges 51 and 52 extend over and are bolted to the flatsurfaces 50 of the drum end walls. TI-Ie lower cavity 66 of each mold 13is sealed by means of agasket 73 anda plate 74 bolted to the ungrooves64, and an upper flat surface 63 extends around the edge of the tray andaround each of the depressions 55' to 57.

THE CLAMPING MECHANISMS A clamping assembly 17 is positioned on eachside of each of the molds 13 as shown in FIGS. 3 to 7, the assemblies 17includes a pair of brackets 77 and 78 mounted to the outer face of oneof the drum end walls at one side of a mold 13, a jaw member 79pivotally mounted on the brackets 77 and 78, and a jaw operating linkage81. The jaw member 79 has a wide head 82 and a narrow shank 84 providedwith a slot 85 at the end thereof. The jaw member pivots on a pin 86extending through the brackets 77, 78 and the shank 84. As best seen inFIG. '6, the head 82 is provided with a rounded contacting edge 87 whichaligns with the groove 59 (or 60) when the jaw is pivoted against themold, to clamp the plastic ribbon 16 between the edge 87 and the edgesof the groove 59 (or 60).

The linkage 81' includes a pair of interconnected members 89 and 90having limited telescopic movement and a spring 91 normally holding thelinkage in the fully extended position. The member 89 is provided with aflat eye end portion 92 which extends into the slot 85 and is connectedto the jaw member by a pin 94. At the inner end of the eye portion 92 ashoulder 95 is formed for engaging one end of the spring 91. THe member90 likewise is provided with an eye portion 96 (FIG. 7) and a shoulder97 for engaging the spring 91. The member 90 includes a tubular portion99 which receives a rod 100 of the member 89 to provide the telescopicmovement. The end of rod 100 and the interior of the member 90 areprovided with interfering formations (not shown) to limit the relativemovement between the members 89 and 90. i

The eye portion 96 of the member 90 is connected .to a link arm 101 asshown in FIG. 7. The link arms 101 have a slot 102 at one end thereoffor receiving the eye portion 96 and have'a bore 104 (FIG. 3) at theother 7 end for receiving ashaft 105. Referring again to FIG. 7,'- allof the link arms 101 associated with the clamping assemblies mounted onthe drum end wall 44 are attached to their respective eye portions 96 bya bolt 103' having a conventional head, while the link arms 101positioned on the other side 'of the drum are attached by means of abolt 106 which has a cam following wheel 107 secured to the headthereof.

The link arms 101 of clamping assemblies 17 positioned to engageopposite sides of the same mold engage opposite ends of the same shaftwhich extends through the end walls.44 and 45 and is mounted in bearings109 and 110 carried thereby. The link arms 101 are rigidly attached tothe shaft 105 so that the shaft and two links rotate as a unit.

As shown in FIGS. 2," 3 and 7, inner and outer cam tracks 111 and 112are mounted on the inner wall of the end plate 11 to control theoperation of the clamping assemblies 17. The cam tracks are radiallyspaced from each other to provide a path 113 therebetween in which thecam following wheels 107 ride. As the drum 12 rotates, the'wheels 107move with the drum and their radial position with respect to the axis ofrotation of the drum is changed by the stationary cam tracks 111, 112 tooperate the jaw members. The path 113 has four different sections: acircular section 114 of large radius during which the jaw membersareclamped; a

longer circular section 115 of lesser radius during which the jaws areopen, and two short transition sections 116 and 117.

As the ribbon 16 is applied to each mold, the section 116 of the campath 113 moves the wheel 107 associated with that mold outwardly causingthe link arms 101 and the shaft 105 to rotate about the axis of theshaft 105. The link arms 101 move the linkage 81 outwardly to pivot thejaw members into the position shown in FIG. to clamp the ribbon to themold. The spring loaded linkage 81 insures that'a uniform clampingpressure is applied without the need for close tolerances. The jawmembers remain in the clamped position while the wheel 107 travelsthrough the path section 114. After the vacuum forming operation iscompleted, the cam tracks move the wheel 107 inwardly through pathsection 117 and the link arms 101 and shaft 105 are rotated in theopposite direction to move the jaw members into the open position. Thejaw members then remain in the open position throughout the section 115of the cam path.

THE HEATING ASSEMBLY 19 With reference to FIGS. 1, 2, and 7, the heatingassembly includes a pair of radiant electric heater units 119 and 120, apivoted supporting frame 121 and a pneumatic actuator 122 for pivotingthe frame. The supporting frame 121 comprises a pair of arms 124 and 125which are joined by a cross member 126. The arms 124 and 125 each carrya pair of outwardly extending bars 127, 128 and 129, 130 respectively,to which the heaters are connected. The arms 124 and 125 are pivotallymounted on a bracket 131 which is bolted to the end plate 11. Thepneumatic actuator 122 includes a cylinder 132 pivotally secured to theend plate 11 by means of a bracket 133 and a piston within the cylindermounted upon a rod 134 which is pivotally connected to the arm 124 ofthe heater supporting frame. When the machine is operating, compressedair is introduced into the bottom of the cylinder 132 to drive thepiston upwardly and rotate the heaters into the position shown in solidlines in the drawings. In this position, the heaters warm the plasticribbon as it passes beneath them and the plastic is softened inpreparation for the vacuum forming process. When the machine stops,compressed air is introduced into the top of the cylinder to drive thepiston downwardly and pivot the heaters away from the ribbon to preventthe ribbon from being melted.

THE VACUUM FORMING APPARATUS As shown in FIG. 7, a vacuum line 135 isconsecutively connected through a rotary coupling and valve assembly 136to each one of twenty hoses 137 extending through holes 138 in the drumwall 45 to the individual molds 13. The rotary coupling and valveassembly 136 includes a stationary circular manifold 139 mounted to theend plate 11 and a rotating collecting ring 140 welded to'the end wall45 of the drum. The collecting ring 140 is provided with twenty recesses141 each connected to one of the hoses 137 and each facing the manifold139. The manifold 139 is provided with a annular passageway 142 which isclosed off from the recesses 141 by a wall section 144 throughout aportion of the manifold. As each mold rotates through that portion of arevolution indicated as vacuum of in FIG. 1, the respective recess 141moves along the portion of the manifold provided with the wall section144. When each mold is rotating through the portion of a revolutionindicated as vacuum on" in FIG. 1, the recess 141 is in fluid flowcommunication with the passageway 142 and the vacuum line is connectedto lower cavity 66 in the molds. The vacuum in the cavity 66draws thesoftened plastic sheet into the cavities 55-57 and holds the plastictrays thus formed in the mold 13.

The manifold 139 is clamped between an outer ring 145 and an inner ring146. The outer ring 145 is supported by a plurality of stepped pins 147(one of which is shown) mounted to the end plate 11. The pins 147 have alarge diameter base portion and a small diameter end portion 148extending into bores 149 provided in the manifold 139. Coil springs 150are positioned on the pin portions 148 to urge the manifold 139 againstthe ring collector 140 to provide a fluid seal therebetween.

Referring again to FIG. 1, the vacuum forming of each tray takes placebetween the time the vacuum is connected to the mold and the time theclamping jaws are opened. The vacuum connection to the mold ismaintained to hold the tray is place throughout the severing andtrimming operations and until the trays are removed by the picking wheel25.

THE TRANSVERSE SEVERING MECHANISM 20 Referring to FIGS. 13 and 14, theheated blade 21 is bolted to a block 152 which is welded to a pair ofsleeves 154 and 155 which are disposed at right angles to the block 152and slide upon rods 156 and 157 respectively. The rods 156 and 157 aresupported by an open rectangular frame 159 which extends from arotatably oscillating shaft 160. The frame 159 includes a two piececlamp 161 secured to the shaft 160, a pair of side members 162 and 163extending from the clamp 161 at right angles to the shaft 160, and amember 164 joining the side members 162 and 163 at their free ends. Therods 156 and 157 extend from the end member 164 to a cross member 165positioned between the side members 162 and 163.

The sleeve 154 is provided with a lug 167 which is connected through aturnbuckle link 169 to a lever arm 170 that is clampedto a rotatablyoscillating shaft 171.

The position of the blade 21 is controlled by the angular orientation ofthe shafts 160 and 171. Rotation of the shaft 160 moves the blade 21toward and away from'the drum 12. Rotation of the shaft 171 moves theblade tangentially with respect to the drum circumference. The angularorientation of the shafts 160 and 171 is controlled by a conventionalcam arrangement. With reference to FIGS. 1 and 12, a pair of cams 172and 173 are mounted on a common shaft 174 with a gear 175. The gear 175is driven from the gear 39 through a dual gear 176 having inner andouter sets of teeth. The shafts 160 and 171 are respectively providedwith cam foll'ower arms 17'7- and' 178 which rotatably oscillate theshafts against the action of springs 179 and 180 operating upon leverarms 181 and 182 secured to he shafts. The shafts 160 and 171 arerotated by the cams to continuously move the blade in an elliptical pathwhich is synchronized with the rotation of the drum.

As each slot 14 moves under the mechanism 20, the blade 21 moves bothtoward the drum and in the direction of drum rotation, enters into theslot 14 to sever the plastic strip connecting adjacent trays, and movesout of the slot while continuing the tangential motion.

The blade continues its outward movement while reversing its tangentialmotion, and finally moves inwardly while continuing this tangentialmotion to complete the elipse.

Referring now to FIGS. through 18, the blade 21 has a central sectionproviding a long straight severing edge 184 and has end sectionsproviding forked severing edges formed by a pair of edge sections 185,186 and 187, 188 respectively which curve in opposite directions fromthe edge 184 through a 90 degree turn. During' the severing operation,the straight severing edge 18 4 moves into the slot 14 to sever theplastic strip 190 (FIG. 17) which joins the adjacent formed trays whilethe edge sections 185, 186 and 187, 188 extend into the grooves 59 and60 to provide rounded corners on the trays.

THE EDGE TRIMMING MECHANISM 22 Referring now to FIGS. 1 and 19, the edgetrimming mechanism includes a sleeve 191 mounted on a shaft 192extending between the end plates 10 and 11, an electric motor 194 boltedto the sleeve, and a pair of arms'195, 196 extending downwardly from thesleeve and supporting a shaftl97 on which the rotating knives 24 aremounted. The blades 24 are positioned to extend into the grooves 59 and60 on each side of the molds 13 and are driven by the motor 194 througha belt 199 and pulleys 200 and 201 to trim off the excess plastic alongthe edges of the trays. The sleeve 191 is keyed to the shaft 192 whichis mounted'in bearings 202 and 203to allow the blades 24 to be rotatedabout the axis of the shaft 192. A third arm 205, formed integrally withthe arm 196, extends generally horizontally from the sleeve 191 and isconnected through a link 206 to an arm 207 mounted upon a shaft 209. Theposition of the knife blades 24 is thus controlled by the angularorientation of the shaft 209. The shaft 209 is journalled in bearings210 and 211 mounted in the end plates 10 and l l and extends past theendiplate 10. The angular position of the shaft 209 is controlled by acam element 212 (FIGS. 1 & 12) mounted on the shaft 174. A cam followingarm 214 mounted-to the shaft 192 is held against the cam element 212 bya spring 215 acting through an arm 216 to rotate the shaft 209 inaccordance with the configuration of the cam element 212. The knifeblades 24 are thus moved toward and away from the drum (FIG. so as tomaintain the penetration of the knives into the grooves 59 and 60constant as the flat faces of the molds 13 moves past the knives.

As shown in FIG. 21, the transverse severing blade 21 produces a slit inthe plastic sheet 16 corresponding to the respective portions of theedge of the blade. The slit includes a straight portion 184', a firstforked end portion composed of slit sections 185' and 186, and acorresponding second forked end portion which is not shown. The blades24 produce slits, one of which is shown at 24, which are aligned withthe extreme ends of the forked end portions (185, l86f) and thereforecompletely separate the individual trays as they trimoff a strip 217 ofexcess-plastic at each edge of the trays.

THE PICKING WHEEL ings 221 and 222 positioned in the end plates 10 and11 respectively and the hub 219 is locked to the shaft by means of a key224. The hub is provided with six bores 225 extending parallel to theshaft (two of which are shown in FIG. 23) and three vacuum picking arms26 are connected to each of the bores 225. Each of the picking arms isprovided with a rubber head 226 which is curved as shown in FIG. 22 tomate with the depressions of the trays 76 and a passageway 227 extendsthrough the arm from the bore 225 to the outer edge of the head 226 Thebores 225 are connected to a vacuum line 229 through a stationarymanifold ring 230 which is pressed against the end of the hub 219 by aplurality of spring loaded connectors 231 supported by a frame member232.The manifold ring 230 is provided with an annular passageway 234which is closed off from the bores 225 by a wall section 235 throughouta portion of the manifold. As each bore 225 rotates through that portionof a revolution indicated as vacuum off in FIG. 22, it is moving alongthe portion of the manifold provided with the wall section 235. Thewheel 25 is driven in 'synchroni sm with the drum so that a row ofpicking arms 26 extends into the depression 55' of each of the finishedtrays 76 as it passes by on the drum. At the time that a row of arms 26engages the trays 76, the bore 225 associated with those arms moves intocommunication with the passageway 234 in the manifold 230. At this timethe vacuum holding that tray in its mold is turned off. The tray is thustransferred from the drum to the picking wheel 25 and carried by thearms 26 to a position above the conveyor belt 27. At this pointthevacuum to the arms 26 is turned off and the tray 76 drops onto theconveyor belt, properly positioned for subsequent filling and packaging,at a distance sufficient to prevent air currents generated by therotating drum from disturbing the tray.

It will be seen from the foregoing that the present invention provides acontinuously operating rotary machine for producing thin plastic packingtrays, wherein the trays are formed in flat faced molds and novelmechanisms are provided for cooperating with the molds to form traysfrom a ribbon of plastic material, and wherein means are included fordepositing the formed trays'on a conveyor in position for filling.

As variouschanges may be made in the form, construction and arrangementof the parts herein, without departing from the spirit and scope of theinvention, and without sacrificing any'of its advantages, it is to beunderstood that all matter herein is to be interpreted as illustratedand not in any limiting sense. i

What is claimed is:

l. A machine for continuously forming thin plastic articles having ashape requiring molding on a flat faced mold comprising a rotary drumcarrying a plurality of outwardly facing flat faced-vacuum form moldsspaced about the periphery of said drum, means providing a transverseslot between adjacent molds, means for continuously rotating said drumat a uniform speed,

means for continuously applying a ribbon of thin plastic material tosaid drum to cover said molds, means for vacuum forming the ribbon intoa series of plastic articles connected together at said transverseslots, and transverse severing means mounted immediately adjacent saiddrum including a blade and means for moving said blade in a repetitiveelongated closed path toconsecutively enter each of said slots and severthe plastic ribbon extending across each of said slots, said blademoving means including means for moving said blade first toward and thenaway from said drum and means for moving said blade in the direction ofrotation of said drum while the blade is moved toward and away from saiddrum so as to match the speed of said blade to that of said drum as theblade enters and leaves each of said slots.

2. A machine according to claim 1 wherein said means for moving saidblade includes a pivoted arm adjacent said drum, means for rotating saidarm toward and away from said drum, means slideably mounting said bladeon said arm for tangential motion with re spect to said drum, and meansfor tangentially moving said blade in synchronization with the motion ofsaid arm and said drum.

3. A machine for continuously forming thin plastic articles having adished configuration with an upper peripheral edge lying within a planecomprising a rotary drum carrying a plurality of outwardly facing flatfaced vacuum form molds spaced about the periphery of said drum, eachmold includes a cavity and a surface surrounding said cavity, means forcontinuously rotating said drum at a uniform speed, means forcontinuously applying a ribbon of thin plastic material to the drum tocover said molds, means for mechanically clamping the ribbon to saidmolds during a portion of each revolution of said drum, means forheating said ribbon during said portion, vacuum producing means fordrawing the heated film into said cavities to form said articles, andsevering means for trimming and separating said articles while on saiddrum said clamping means including a plurality of clamps carried by saiddrum, a pair of clamps being provided for each of said molds, and a cammechanism for consecutively operating each pair of clamps to clamp asection of the ribbon before that section is heated and to disengageafter the articles are formed and before the operation of said severingmeans, the clamps of each of said pairs being mounted on opposite sidesof said mold.

4. A machine according to claim 3 wherein a transverse slot is providedbetween'adjacent molds and each mold is provided with a pair of groovesextending along opposite edges of said mold and intersecting said slotsat right angles, each of said clamps are provided with a jaw memberhaving a ribbon contacting edge aligned with one of said grooves toclamp the ribbon between said contacting. edge and the edges of saidgroove, and knife means positioned within each of said grooves to trimthe edges of said ribbon after said clamps have disengaged said ribbon.

5. A machine according to claim 4 wherein said severing means includestransverse severing means, said transverse severing means being mountedimmediately adjacent said drum and including a blade and means formoving said blade in a repetitive elongated closed path to consecutivelyenter each of said slots and sever the plastic extending across each ofsaid slots.

' 6. A machine according to claim 5 wherein said blade has a straightcentral portion and forked end portions, said central portion beingreceived by said slots during the severing operations, said end portionseach providing a pair of severing edges curving in opposite directionsfrom said central portion through a 90 degree turn to be received bysaid grooves during the severing operations and thus provide roundedcorners on said articles.

7. A machine according to claim 4 wherein said edge trimming meansincludes a knife positioning mechanism for maintaining the penetrationof said knife means into said grooves substantially constant as saidmolds move past said knives.

8. A machine for forming thin plastic articles comprising a rotary drumcarrying a plurality of outwardly facing vacuum form molds spaced aboutthe periphery of said drum, each of said molds being provided with acavity and a surface surrounding said cavity defining a flatplane,=means for continuously rotating said drum at a uniforni speed,means for continuously applying a ribbon of thin plastic material to thedrum to cover said molds, means for mechanically clamping the ribbon tosaid molds during a portion of each revolution of said drum, means forheating said ribbon during said portion, vacuum producing means fordrawing the heated film into said cavities to form said articles,severing means for trimming and separating said articles, and vacuumoperated picking means adjacent said drum for removing said articlesfrom said molds including a rotary coupling and at least one vacuum armextending radially from said coupling to consecutively engage each ofthe articles in said cavities, said coupling being driven tocontinuously rotate through 360 in synchronism with said drum andincluding valving to render said vacuum arm effective from the point ofengagement with an article through a portion of a revolution of saidcoupling to a discharge point, whereby the articles are consecutivelyremoved from said drum and transported to the discharge point.

9. A machine according to claim 8 wherein said valving in said rotarycoupling renders said vacuum arm ineffective when said arm extendsvertically downward and wherein a conveyor is positioned beneath saidpicking means, whereby the articles are deposited on said conveyor in anupright position convenient for subsequent filling.

10. A machine for continuously forming thin plastic articles having adished configuration with an upper peripheral edge lying within a planecomprising a rotary drum carrying a plurality of outwardly facing flatfaced vacuum form molds spaced about-the periphery of said drum, eachmold includes a cavity and a surface surrounding said cavity, means forcontinuously rotating said drum at a uniform speed, means forcontinuously applying a ribbon of thin plastic material to the drum tocover said molds, means for mechanically clamping the ribbon to saidmolds during a portion of each revolution of said drum means for heatingsaid ribbon during said portion, vacuum producing means for drawing theheated film into said cavities to form said articles, and severing meansfor trimming said articles while on saiddrum, said clamping meansincluding a plurality of clamps carried by said drum, a pair of clampsbeing provided for each of said molds, and a cam mechanism forconsecutively operating each pair of clamps to clamp a section of theribbon before that section is heated and to disengage after the articlesare formed and before the operation of said severing means, the clampsof each of said pairs being mounted on opposite sides of said mold, eachmold being provided with a pair of grooves extending along oppositeedges of said mold, each of said clamps being provided with a jaw memberhaving a ribbon contacting edge aligned with one of said grooves toclamp the ribbon between said contacting edge and to the edges of saidgroove, said severing means including knife means positioned within eachof said grooves to trim the edges of said ribbon after said clamps havedisengaged said ribbon.

, NITED STATES T PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3, 771,938 Dated November 13, 1973 lnventofls ALBERT A. PINTO ET. AL.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby "corrected as shown below:

On the cove? sheet, insert 73] Assignee:

Nabisco, Inc. a corporation of New Jerseyv Signed and sealed this 6th(121' of August 19.74.

(SEAL) r I L Attest:

MCCQY M. GIBSON, JR. C. MARSHALL DANN Attesting Officer A 7 Commissionerof Patents FOIRM po-wso (10-69) USCOMM-DC 60376-P69 w U.$l GOVERNMENTHUNT NG OFFICE I9! 0-366-334,

1. A machine for continuously forming thin plastic articles having ashape requiring molding on a flat faced mold comprising a rotary drumcarrying a plurality of outwardly facing flat faced vacuum form moldsspaced about the periphery of said drum, means providing a transverseslot between adjacent molds, means for continuously rotating said drumat a uniform speed, means for continuously applying a ribbon of thinplastic material to said drum to cover said molds, means for vacuumforming the ribbon into a series of plastic articles connected togetherat said transverse slots, and transverse severing means mountedimmediately adjacent said drum including a blade and means for movingsaid blade in a repetitive elongated closed path to consecutively entereach of said slots and sever the plastic ribbon extending across each ofsaid slots, said blade moving means including means for moving saidblade first toward and then away from said drum and means for movingsaid blade in the direction of rotation of said drum while the blade ismoved toward and away from said drum so as to match the speed of saidblade to that of said drum as the blade enters and leaves each of saidslots.
 2. A machine according to claim 1 wherein said means for movingsaid blade includes a pivoted arm adjacent said drum, means for rotatingsaid arm toward and away from said drum, means slideably mounting saidblade on said arm for tangential motion with respect to said drum, andmeans for tangentially moving said blade in synchronization with themotion of said arm and said drum.
 3. A machine for continuously formingthin plastic articles having a dished configuration with an upperperipheral edge lying within a plane comprising a rotary drum carrying aplurality of outwardly facing flat Faced vacuum form molds spaced aboutthe periphery of said drum, each mold includes a cavity and a surfacesurrounding said cavity, means for continuously rotating said drum at auniform speed, means for continuously applying a ribbon of thin plasticmaterial to the drum to cover said molds, means for mechanicallyclamping the ribbon to said molds during a portion of each revolution ofsaid drum, means for heating said ribbon during said portion, vacuumproducing means for drawing the heated film into said cavities to formsaid articles, and severing means for trimming and separating saidarticles while on said drum said clamping means including a plurality ofclamps carried by said drum, a pair of clamps being provided for each ofsaid molds, and a cam mechanism for consecutively operating each pair ofclamps to clamp a section of the ribbon before that section is heatedand to disengage after the articles are formed and before the operationof said severing means, the clamps of each of said pairs being mountedon opposite sides of said mold.
 4. A machine according to claim 3wherein a transverse slot is provided between adjacent molds and eachmold is provided with a pair of grooves extending along opposite edgesof said mold and intersecting said slots at right angles, each of saidclamps are provided with a jaw member having a ribbon contacting edgealigned with one of said grooves to clamp the ribbon between saidcontacting edge and the edges of said groove, and knife means positionedwithin each of said grooves to trim the edges of said ribbon after saidclamps have disengaged said ribbon.
 5. A machine according to claim 4wherein said severing means includes transverse severing means, saidtransverse severing means being mounted immediately adjacent said drumand including a blade and means for moving said blade in a repetitiveelongated closed path to consecutively enter each of said slots andsever the plastic extending across each of said slots.
 6. A machineaccording to claim 5 wherein said blade has a straight central portionand forked end portions, said central portion being received by saidslots during the severing operations, said end portions each providing apair of severing edges curving in opposite directions from said centralportion through a 90 degree turn to be received by said grooves duringthe severing operations and thus provide rounded corners on saidarticles.
 7. A machine according to claim 4 wherein said edge trimmingmeans includes a knife positioning mechanism for maintaining thepenetration of said knife means into said grooves substantially constantas said molds move past said knives.
 8. A machine for forming thinplastic articles comprising a rotary drum carrying a plurality ofoutwardly facing vacuum form molds spaced about the periphery of saiddrum, each of said molds being provided with a cavity and a surfacesurrounding said cavity defining a flat plane, means for continuouslyrotating said drum at a uniform speed, means for continuously applying aribbon of thin plastic material to the drum to cover said molds, meansfor mechanically clamping the ribbon to said molds during a portion ofeach revolution of said drum, means for heating said ribbon during saidportion, vacuum producing means for drawing the heated film into saidcavities to form said articles, severing means for trimming andseparating said articles, and vacuum operated picking means adjacentsaid drum for removing said articles from said molds including a rotarycoupling and at least one vacuum arm extending radially from saidcoupling to consecutively engage each of the articles in said cavities,said coupling being driven to continuously rotate through 360* insynchronism with said drum and including valving to render said vacuumarm effective from the point of engagement with an article through aportion of a revolution of said coupling to a discharge point, wherebythe articles are consecutively removed from said drum and transported tothe diScharge point.
 9. A machine according to claim 8 wherein saidvalving in said rotary coupling renders said vacuum arm ineffective whensaid arm extends vertically downward and wherein a conveyor ispositioned beneath said picking means, whereby the articles aredeposited on said conveyor in an upright position convenient forsubsequent filling.
 10. A machine for continuously forming thin plasticarticles having a dished configuration with an upper peripheral edgelying within a plane comprising a rotary drum carrying a plurality ofoutwardly facing flat faced vacuum form molds spaced about the peripheryof said drum, each mold includes a cavity and a surface surrounding saidcavity, means for continuously rotating said drum at a uniform speed,means for continuously applying a ribbon of thin plastic material to thedrum to cover said molds, means for mechanically clamping the ribbon tosaid molds during a portion of each revolution of said drum means forheating said ribbon during said portion, vacuum producing means fordrawing the heated film into said cavities to form said articles, andsevering means for trimming said articles while on said drum, saidclamping means including a plurality of clamps carried by said drum, apair of clamps being provided for each of said molds, and a cammechanism for consecutively operating each pair of clamps to clamp asection of the ribbon before that section is heated and to disengageafter the articles are formed and before the operation of said severingmeans, the clamps of each of said pairs being mounted on opposite sidesof said mold, each mold being provided with a pair of grooves extendingalong opposite edges of said mold, each of said clamps being providedwith a jaw member having a ribbon contacting edge aligned with one ofsaid grooves to clamp the ribbon between said contacting edge and to theedges of said groove, said severing means including knife meanspositioned within each of said grooves to trim the edges of said ribbonafter said clamps have disengaged said ribbon.